Artificial Muscle for Soft Robots

Material science and mechanical engineering researchers at Colorado University, Boulder, have developed a remarkable system that imitates the function of biological muscle. The devices are described as “hydraulically amplified self-healing electrostatic” actuators, or HASEL for short. They consist of a soft pouch – foil, elastomer, or other soft/flexible material – filled with electrically insulating liquid […]

Material science and mechanical engineering researchers at Colorado University, Boulder, have developed a remarkable system that imitates the function of biological muscle. The devices are described as “hydraulically amplified self-healing electrostatic” actuators, or HASEL for short.

They consist of a soft pouch – foil, elastomer, or other soft/flexible material – filled with electrically insulating liquid – canola oil, for example. When a charge is applied, the liquid displaces, changing the shape of the pouch it’s contained in. The devices are capable of performance that surpasses that of biological muscle fibers. They can be actuated more rapidly and can exert more force. One HASEL design can lift a gallon of water several times per second. Another design can be used to grasp and reposition very delicate objects – like a raspberry.

One significant advantage of HASEL actuators is that they are self-healing if damaged by electrical discharge. There are other types of soft actuators – known as dielectric elastomer actuators – that are controlled by voltage. The problem with those is that they use a solid insulating layer that fails catastrophically from electrical damage. HASEL actuators, on the other hand, immediately recover their insulating properties if they are electrically damaged. That characteristic allows the devices to scale to exert large amounts of force.

Robotics are going to become ever more significant in the coming years. Soft robots are especially suited for applications in the medical device field. Look for more advances in soft-robotic technologies. There is huge potential here.